Suspending systems for suspending solid particles in liquid compositions have been employed in specific types of cleaning and personal care compositions in the past. For example, suspending systems comprising surfactant phases and/or surfactant structuring liquids have been incorporated into liquid detergent compositions.
Examples of such surfactant-based suspending systems are described in EP 442 549 B1, U.S. Pat. No. 4,828,747, EP 160 342 B2, EP 386 566 A1, U.S. Pat. No. 5,391,324, EP 668 903 and 5,409,632, which all deal with the suspension of preformed poorly water soluble peracids using surfactant phases. Such surfactant phases are made using (i) one or more nonionic surfactants (low electrolyte) or (ii) combinations of anionic and/or nonionic surfactants with fatty acids and/or electrolytes.
GB 2279660 describes the use of xanthan gum as a suspending agent for solid particles in a liquid detergent product. More specifically, GB 2279660 discloses a stable, pourable aqueous liquid laundry detergent composition comprising xanthan gum (a polysaccharide polymer) for phase stability, along with a specific pH jump system for cleaning performance and product bleach stability, in a peroxyacid-containing suspension. This is accomplished without the use of a stability enhancing polymer which is a copolymer of a hydrophobic and a hydrophilic monomer.
U.S. Pat. Nos. 4,992,194 and 5,073,285, both Liberati et al, issued Feb. 12, 1991 and Dec. 17, 1991, respectively, describe aqueous structured heavy duty liquid detergent formulations which contain solid, particulate, substantially water-insoluble organic peroxyacid, surfactant combinations, pH adjusting systems, and selected decoupling polymers.
U.S. Pat. No. 4,879,057 to Dankowski et al, issued Nov. 7, 1989 discloses aqueous bleaching suspensions including peroxycarboxylic acid suspended in a carrier liquid in the presence of an organic thickening agent and of an acidifying agent. The suspensions contain agar or xanthan polysaccharide as a thickening agent, and a hydrate-forming neutral salt.
It is well known that aqueous liquid laundry detergent products which contain suspended solids such as solid, substantially water-insoluble peroxyacid can have phase stability problems, particulary across the varying environmental temperatures to which such products may be exposed.
A further problem is product and wash pH, since low product pH is required for bleach stability while alkaline wash pH is advantageous for cleaning and bleaching efficacy (see U.S. Pat. No. 4,259,201, Cockrell).
Additionally, when product detergent surfactant levels are increased in such compositions for better cleaning and bleaching performance, product viscosity often increases to unacceptable levels.
Lastly, suspensions of solid particulates, especially peroxycarboxylic acids, often times are plagued by eye irritation problems.
However, the use of polymeric stabilization systems of the present invention, especially ethoxylated polymers and/or low levels (<1%) of ethoxylated nonionics in aqueous liquid detergent compositions to stabilize solid particles, such as substantially water-insoluble peroxycarboxylic acids and/or to reduce eye irritation of the compositions is not known, nor has it been suggested in the prior art.
Accordingly, there is a need for an aqueous liquid detergent composition comprising one or more particulate solids such as peroxycarboxylic acids (“peracid”) and a polymeric stabilization system, and a method for laundering fabrics using such a composition.